Flexible pipe joint

ABSTRACT

A method and apparatus for securing a flexible pipe to a further flexible pipe in an end-to-end configuration, wherein the apparatus includes and the method utilizes an elongate tubular element having a first and second end and an outer surface comprising a raised central region. At least one vent passage extends at least partially across the raised central region.

BACKGROUND OF THE INVENTION

The present invention relates to a method and apparatus for securing oneflexible pipe to another flexible pipe in an end-to-end configuration.In particular, but not exclusively, the present invention relates to amethod of joining lengths of flexible pipe together to form a pipelinewhereby gases trapped in an annulus region of a flexible pipe in onepart of the pipeline can be transmitted into a corresponding annulusregion in another part or parts of the pipeline.

Un-bonded flexible pipe is well-known and there are many uses for whichsuch flexible pipe may be utilised. For example, transmitting fluid suchas a production fluid like oil or gas from one location to another. Suchflexible pipe may be used for offshore purposes as well as onshore orover land purposes. Typically such flexible pipe includes an inner fluidretaining layer, often referred to as a liner or barrier layer, whichhelps prevent fluid flow radially outwards from the bore. This layer hasan inner diameter defining a bore along which fluid can flow. One ormore armour layers are typically formed around the fluid retaininglayer. The armour layer or layers are typically, but not exclusively,formed by winding steel strip about the fluid retaining layer. Thearmour layer or layers provide pressure reinforcement to prevent burstthrough of the inner fluid retention layer as well as preventingcollapse of the flexible pipe due to external pressures. Additionallythe armour layer can provide tensile strength to resist longitudinalforces of either extension or contraction on the flexible pipe. Theflexible pipe also typically includes an outer sheath which is arrangedto prevent ingress of fluid and/or contaminants from an environmentwhere the flexible pipe is located.

The region between the outer sheath and inner fluid retaining layerdefines an annulus region extending along the length of the portion offlexible pipe in which the armour layer or layers are located. One wellknown problem associated with this annular layer is that gas whichpenetrates through the fluid retaining layer from the transported fluidcollects in the annular region. Also where the flexible pipe is utilisedin an environment including undesirable gas such gas can permeatethrough the outer sheath and likewise be trapped in the annulus region.The trapped gases can collect and on occasion can cause rupturing in theflexible pipe or can degrade performance of the flexible pipe over timein many known ways. For this reason gases trapped in the annulus ofun-bonded flexible pipe require venting. This has been achieved in thepast by securing adjacent portions of flexible pipe together in a waysuch that a gas pathway is formed between corresponding annulus regionsin adjacent flexible pipes. One or more valves have then been used tovent the gases trapped at one or more predetermined locations. In thepast the pathway between connected pipes has been provided by jumpertubes. The configuration of the jumper tubes used has in the past beendetermined by the mechanism by which portions of flexible pipe have beensecured to one another in an end-to-end configuration. For example, whenend fittings have been used jumper tubes have required vent holes to bemachined in each end fitting so that the jumper tube can transmit gasesfrom one pipe end past the end fittings to the other pipe end.

Over the entire length of a pipeline formed by two or more portions offlexible pipe connected together in an end-to-end configuration thegases that accumulate in the annulus space can thus be directed to oneor both ends of the pipeline or to other locations where an exit valveis located.

Unfortunately such jumper tubes are often fragile and tend to createobstructions when performing rehabilitation work. Broken jumper tubes ormissing plugs in an end fitting can cause harmful gases to escape in anuncontrolled fashion or allow moisture into the flexible pipe annuluswhich potentially damages the flexible pipe and degrades performance.

BRIEF SUMMARY OF THE INVENTION

It is an aim of the present invention to at least partly mitigate theabove-mentioned problems.

It is an aim of embodiments of the present invention to provide a methodfor securing an end of a first portion of flexible pipe to an end of afurther portion of flexible pipe in an end-to-end configuration wherebygases trapped in an annulus region of each portion of flexible pipe arein fluid communication and can thus be vented at an end or other desiredlocations of the pipeline formed by the co-connected the portions offlexible pipe.

It is an aim of embodiments of the present invention to provide aflexible pipe connector which can be used to connect one portion offlexible pipe to a further portion of flexible pipe.

It is an embodiment of the present invention to provide a method andapparatus which enables gases trapped in the annulus regions ofun-bonded flexible pipe to be transmitted to one or more end regions ormid sections where such gases can be vented.

According to a first aspect of the present invention there is providedapparatus for securing a flexible pipe to a further flexible pipe in anend-to-end configuration, comprising:

an elongate tubular element comprising a first and second end and anouter surface comprising a raised central region; and

at least one vent passage extending at least partially across the raisedcentral region.

According to a second aspect of the present invention there is providedA method of securing a flexible pipe to a further flexible pipe in anend-to-end configuration, comprising the steps of:

urging an end of a first flexible pipe into an annulus region between afirst end of an elongate tubular element and a first jacket member;

urging an end of a second flexible pipe into a further annular regionbetween a second end of the elongate tubular element and a second jacketmember; and

providing a vent path from an annular region of the first flexible pipeto a corresponding annular region of the second flexible pipe via a ventpassage extending at least partially across a raised central region ofthe elongate tubular element.

Embodiments of the present invention provide a method by which externaljumper tubes can be eliminated from a pipeline. Where adjacent flexiblepipes are joined together venting paths are incorporated within aconnector piece so that gases can be transmitted through the midlineconnection.

Embodiments of the present invention provide a vent path which isinternal so as to eliminate extra tubes and any external obstructions.

Embodiments of the present invention will now be described hereinafter,by way of example only, with reference to the accompanying drawings inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a flexible pipe;

FIG. 2 illustrates a pipeline;

FIG. 3 illustrates a midline connector;

FIG. 4 illustrates a flexible pipe connected to a connector;

FIG. 5 illustrates part of a midline connector;

FIGS. 6, 6A and 6B illustrates alternate embodiments of a part of theconnector;

FIG. 7 illustrates an alternative midline connector; and

FIG. 8 illustrates alternative ring shapes.

In the drawings like reference numerals refer to like parts.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a cross sectional view of a portion of flexible pipe10. It will be understood that the longitudinal length of the flexiblepipe can be from a few metres to a few kilometres or more in length. Aninnermost fluid retaining layer 11 has an inner surface 12 which definesa central bore 13 along which fluid can flow. The flexible pipe isapplicable to the transportation of a wide variety of fluids such aswater or production fluids such as oil or gas. One or more inner layers(not shown) may be provided under the fluid retaining layer.

An outer sheath 14 provides an outer protection layer which preventsingress of contaminants as well as providing physical protection againstattack from an environment 15 outside the flexible pipe.

Three layers 16 a, 16 b, 16 c of armour protection are formed between anouter surface 17 of the fluid retaining layer and an inner surface 18 ofthe outer sheath 14. An annular region 19 is thus formed between theinner surface 18 of the outer sheath and outer surface 17 of the fluidretaining layer 11.

It will be understood that the armour layers 16 a-16 c may be providedby one or more layers of wound strips according to further embodimentsof the present invention. Also whilst the strips illustrated in FIG. 1are shown as having a substantially flat cross section, it will beunderstood that strip having predetermined cross sections may be usedaccording to further embodiments of the present invention. Such stripsmay or may not interlock to some extent.

FIG. 2 illustrates how a pipeline 20 can be formed by joining portionsof pipeline 101, 102 together in an end-to-end configuration via amid-line connector 21. It will be understood that a pipeline may beformed by two or more portions of flexible pipe 10 _(1, 2 . . . n) eachjoined to one or two adjacent portions of flexible pipe by a respectiveconnection.

FIG. 3 illustrates a connector 21 useable to secure adjacent portions offlexible pipe together in more detail. The connector includes an innercylindrical tube 30 having a substantially cylindrical inner surface 31and an outer surface 32 which is inwardly tapered at a first open end 33and a further open end 34. The taper helps locate the pipe ends withrespect to the connector during connection.

A central region of the outer surface of the tube is stepped outwardlyto form a raised central section 35. The raised portion 35 is itselfstepped radially outwardly at one end 36 to form an abutment surface 37.

Prior to securing to a flexible pipe a ring 38 is slipped over the firstend 33 of the tube 30. The ring has an inner diameter provided by aninner cylindrical surface having a dimension just big enough to slipover the outer diameter of the narrow end of the outer surface of theraised portion 35 of the tube. An end 39 of the ring abuts with thesurface 37 of the wide end of the raised portion 35. This duly locatesthe ring in position.

The ring 38 has a central cut out region to aid handling. Other profilesof ring may be utilised as discussed herein below.

Subsequent to the fitting of the ring 38 about the raised centralsection of the cylindrical tube a first jacket 40 and further jacket 41are secured to the connecting ring via a weldment, adhesive, bolt orscrew or other such fastening mechanism. Each jacket has a respectiveopen mouth 42, 43 and is generally cylindrical in shape with an inwardlytapered end which tapers radially inwardly at one end of the jacket.Subsequent to the jackets being secured to the ring an annulus region isdefined at each end of the midline connector. The annular region 44 at afirst end of the connector is defined between an outer surface of thecylindrical tube and an inner surface of a respective jacket 40. Afurther annulus region 45 is defined between an outer surface of afurther end of the tube and an inner surface of a remaining jacket 41.It will be understood that the jackets may be secured to other locationsof the connector 21.

FIG. 4 illustrates how an end of a flexible pipe 102 may be secured atone end of the midline connector 21 between a jacket 41 secured to thering 38 mounted on the midline connector 21. Subsequent to securing thejacket 41 to the connector ring via the weldment 46 or other suchfastening, an end of the flexible pipe 102 is introduced into theannulus region 45. Subsequently during a swaging process the jacket 41is deformed by a force exerted as shown by arrow A in FIG. 4 which locksthe pipe end in the connector. It will be appreciated that otherfastening techniques, such as bolting, gluing, welding or the like, maybe utilised to secure the end of the flexible pipe to the jacket 41 andtube 30.

As illustrated in FIG. 4 an open end of the flexible pipe is thus influid communication with a space 47 which is a part of the annularregion between the jacket and cylindrical body 30. As such the annularregion formed between the outer surface 17 of the fluid retaining layerand inner surface 18 of the outer sheath will vent directly into thisspace 47. From there fluid flow occurs via passageways formed as boresor slots through the cylindrical body 30 and/or ring 38 to acorresponding space at the other end of the midline connector. Fromthere fluid venting from one flexible pipe can pass into thecorresponding annular region of the adjacent flexible pipe portion.

FIG. 5 illustrates a further view of a midline connector 21 beforejackets are attached. The connector has a cylindrical body 30 having asubstantially cylindrical inner surface 31 which defines an internalbore along which fluid can flow through the connector and along thepipeline in general. The outer surface 32 of the connector is taperedinwardly towards a first open end to thereby define an inwardlyextending region 50 extending circumferentially around the body. At afurther open end 34 a further circumferentially extending tapered region51 is formed. A central region of the outer surface of the cylindricalbody is stepped radially outwardly at a first end 52 to provide a raisedouter surface which is generally cylindrical. This extends to a furtherend region 36 of the central raised section 35 of the connector. Asillustrated in FIG. 5 an end 52 of the raised section thus extendsradially outwardly less than the other end 36 of the raised section. Aring 38 is slid over the central raised region from the first end 52 andalong the raised section until the ring abuts with the radiallyoutwardly extending step at the further end of the raised region. Thisduly locates the ring in position.

As illustrated in FIG. 5 slots 55 are formed in the raised centralsection of the connector. One or more slots can be preformed and asillustrated in FIG. 5 the slots extend across the whole width of thecentral raised section. It will be appreciated that the slots may beformed less than the whole way through the raised portion according tofurther embodiments of the present invention. The ring 38 covers acentral region of each of the slots when duly located.

FIG. 6 illustrates the raised central portion of the connector and theslots 55 prior to the ring being put in position. FIG. 6 alsoillustrates how an outer surface of the raised central section isstepped. It will be appreciated that in use the slots 55 provide a ventpassage along which fluid such as gas or liquid can flow when thepipeline is in operation. To this end the vent passage can, instead of aslots, be formed as a through bore or partial through bore through theraised central section of the connector. Still further alternativeembodiments include one or more slots or bores formed at one or morepredetermined locations on the ring which communicate with partialmating passages formed by slots or bores in the raised central region ofthe connector, as illustrated in FIG. 6B. It will be appreciated thatthe raised central region of the connector may be integrally formed withthe cylindrical body as illustrated in FIGS. 5 and 6 or alternativelymay be a separate unitary or multi-piece unit secured to the cylindricalbody prior to application of the ring.

FIG. 7 illustrates an alternative embodiment of the connector shown inFIG. 6 and illustrates how the slots 55 may be alternatively formed ascurved or labyrinthine passageways through the raised section. Althoughthe curved slot 70 illustrated in FIG. 7 is shown passing the whole waythrough the raised section in the middle of the connector alternativeembodiments of the present invention can make use of one or more curvedslots which pass only a partial way through the raised portion.

Embodiments of the present invention eliminate flanged or welded endfittings for the purpose of connecting two sections of flexible pipetogether. The connector is installed as a coupling that reduces leakpotential caused by two flanged end fittings which would otherwise beused according to the prior art. The midline connector also eliminatesthe need for welding two separate end fittings together as per the priorart.

The connector “grabs” two ends of flexible pipe from the inner and outerdiameters. The tubular body contacts an inner diameter of each flexiblepipe and a centering ring is used to hold the connector during a swagingoperation. External jackets are welded to the centering ring and thesecan be used to grab the outer diameter of the flexible pipe.

Venting is incorporated between the inner body and centering ring bymeans of slots or other types of passage. The slots can be cut axiallyalong a section of the body outer diameter or alternatively can behelically formed. Slots may be on the raised portion of the cylindricalbody and/or an inner surface of the ring, as shown in FIGS. 5, 6, 6A, 6Band 7.

The body and centering ring are concentrically mated together and formvent paths completely enclosed within the midline connector.

Slots machined on the outer diameter of the body may alternatively takethe form of a helix or labyrinthine structure wrapping around the raisedsurface of the body outer diameter. This is advantageous during amanufacturing process as lathes may be used to machine the body withoutindependent milling capabilities.

Alternative embodiments of the present invention utilise a design whichincludes mating the body and centering ring by loose fitting threadswhich allow gases to pass through the helical gaps in the threads.

FIG. 8 illustrates alternative cross sectional views of a centering ring38. FIG. 8b illustrates the cross section of ring illustrated in theprevious drawings. FIG. 8a illustrates a substantially cylindrical ringwith a radially outwardly stepped raised portion 81 at a predeterminedend. As shown in FIG. 8b the outer surface of the ring may alternativelyhave a raised portion 82, 83 at each longitudinal end. FIG. 8cillustrates a raised portion 84 which extends radially outwardly from asubstantially cylindrical body within the ends of the ring but offsetfrom a central point. FIG. 8d illustrates how a substantiallycylindrical ring may be utilised. It will be appreciated that furthercross sections of ring may be utilised according to still furtherembodiments of the present invention.

Prior art connections for securing flexible pipe together havetransmitted gases between two separate sections of flexible pipe byincorporating external components connected to end fittings. Theseexternal components, such as jumper tubes, were connected to jackets orother portions of a connector by either welding or threading components.The present invention eliminates all external components and the processof connecting external components to end fittings. The internal natureof the venting provided by embodiments of the present invention providesa more direct path for the gas transmittal, thus reducing thepossibility of an obstructed path. Pressure build-up within annulusspaces caused by blocked gas can cause rupture of the outer shield layerof the flexible pipe and this is avoided according to embodiments of thepresent invention.

The midline connection is thus a multi-part system that “grabs” two endsof flexible pipe from the inner and outer diameters. The midlineconnection includes an inner body formed as a tube that contacts aninner diameter of the pipe. A centering ring is used to hold the midlineconnection during a swaging operation and external jackets are welded tothe centering ring. These external jackets are used to grab an outerdiameter of each flexible pipe.

Throughout the description and claims of this specification, the words“comprise” and “contain” and variations of the words, for example“comprising” and “comprises”, means “including but not limited to”, andis not intended to (and does not) exclude other moieties, additives,components, integers or steps.

Throughout the description and claims of this specification, thesingular encompasses the plural unless the context otherwise requires.In particular, where the indefinite article is used, the specificationis to be understood as contemplating plurality as well as singularity,unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties orgroups described in conjunction with a particular aspect, embodiment orexample of the invention are to be understood to be applicable to anyother aspect, embodiment or example described herein unless incompatibletherewith.

We claim:
 1. A system, comprising: a first flexible pipe, wherein thefirst flexible pipe comprises: a first fluid retaining layer; a firstouter sheath; a first pipe annular region formed between the first fluidretaining layer and the first outer sheath; and a first armor layerdisposed in the first pipe annular region; a second flexible pipe,wherein the second flexible pipe comprises: a second fluid retaininglayer; a second outer sheath; a second pipe annular region formedbetween the second fluid retaining layer and the second outer sheath;and a second armor layer disposed in the second pipe annular region; anda connector configured to couple the first flexible pipe and the secondflexible pipe, wherein the connector comprises: an inner tube having afirst end and a second end; a ring disposed over a central region of theinner tube between the first end and the second end of the inner tube; afirst jacket coupled to a first end of the ring; a second jacket coupledto a second end of the ring; a first connector annular region formedbetween the first end of the inner tube and the first jacket, whereinthe first flexible pipe is disposed in the first connector annularregion such that the first pipe annular region is in fluid communicationwith the first connector annular region; a second connector annularregion formed between the second end of the inner tube and the secondjacket, wherein the second flexible pipe is disposed in the secondconnector annular region such that the second pipe annular region is influid communication with the second connector annular region; and a ventpassage formed in the inner tube, the ring, or both, such that the firstconnector annular region is in fluid communication with the secondconnector annular region via the vent passage.
 2. The system of claim 1,wherein the inner tube comprises an abutment surface extending radiallyoutwardly from an outer surface of the inner tube, and wherein the ringis configured to abut against the abutment surface when disposed overthe central region of the inner tube.
 3. The system of claim 1, whereinthe central region has an inner surface, wherein the inner tube and thecentral region are separate components that are securely connected toone another along the inner surface of the central region to form aunitary tubular element, and wherein the unitary tubular element isformed prior to any portion of the ring being located over any portionof the central region.
 4. The system of claim 1, wherein the ventpassage comprises a slot formed in an outer surface of the centralregion and extending at least partially across the central region, orformed in an inner surface of the ring and extending at least partiallyover the central region, or both.
 5. The system of claim 1, wherein thecentral region of the inner tube comprises a raised portion formed on anouter surface of the inner tube, and wherein the ring is disposedentirely over the raised portion of the central region.
 6. The system ofclaim 1, wherein the first jacket is coupled to the first flexible pipevia at least one of swaging, bolting, gluing, or welding, and the secondjacket is coupled to the second flexible pipe via at least one ofswaging, bolting, gluing, or welding.
 7. A system, comprising: aconnector configured to couple a first flexible pipe having a first pipeannular region and a second flexible pipe having a second pipe annularregion, wherein the connector comprises: an inner tube having a firstend and a second end; a ring disposed over a central region of the innertube between the first end and the second end of the inner tube; a firstjacket coupled to a first end of the ring; a second jacket coupled to asecond end of the ring; a first connector annular region formed betweenthe first end of the inner tube and the first jacket, wherein the firstconnector annular region is configured to receive the first flexiblepipe such that the first pipe annular region is in fluid communicationwith the first connector annular region; a second connector annularregion formed between the second end of the inner tube and the secondjacket, wherein the second connector annular region is configured toreceive the second flexible pipe such that the second pipe annularregion is in fluid communication with the second connector annularregion; and a vent passage formed in the inner tube, the ring, or both,such that the first connector annular region is in fluid communicationwith the second connector annular region via the vent passage.
 8. Thesystem of claim 7, wherein the ring comprises a central cut out regionto aid in handling the ring.
 9. The system of claim 7, wherein the innertube comprises an abutment surface extending radially outwardly from anouter surface of the inner tube, and wherein the ring is configured toabut against the abutment surface when disposed over the central regionof the inner tube.
 10. The system of claim 7, wherein the central regionhas an inner surface, wherein the inner tube and the central region areseparate components that are securely connected to one another along theinner surface of the central region to form a unitary tubular element,and wherein the unitary tubular element is formed prior to any portionof the ring being located over any portion of the central region. 11.The system of claim 7, wherein the vent passage comprises a slot formedin an outer surface of the central region and extending at leastpartially across the central region, or formed in an inner surface ofthe ring and extending at least partially over the central region, orboth.
 12. The system of claim 7, wherein the central region of the innertube comprises a raised portion formed on an outer surface of the innertube, and wherein the ring is disposed entirely over the raised portionof the central region.
 13. The system of claim 7, wherein the ring iscoupled to the inner tube via threads, and the vent passage compriseshelical gaps in the threads.
 14. A method, comprising: disposing a ringover a central region of an inner tube between a first end and a secondend of the inner tube; coupling a first jacket to a first end of thering, thereby forming a first connector annular region between the firstend of the inner tube and the first jacket; coupling a second jacket toa second end of the ring, thereby forming a second connector annularregion between the second end of the inner tube and the second jacket;inserting a first flexible pipe into the first connector annular regionsuch that a first pipe annular region of the first flexible pipe is influid communication with the first connector annular region; inserting asecond flexible pipe into the second connector annular region such thata second pipe annular region of the second flexible pipe is in fluidcommunication with the second connector annular region; coupling thefirst flexible pipe to the first jacket; coupling the second flexiblepipe to the second jacket; and venting the first connector annularregion to the second connector annular region via a vent passage formedin the inner tube, the ring, or both.
 15. The method of claim 14,comprising abutting the ring against an abutment surface extendingradially outwardly from an outer surface of the inner tube when the ringis disposed over the central region of the inner tube.
 16. The method ofclaim 14, wherein the central region has an inner surface, the innertube and the central region are separate components, and comprisingcoupling the central region to the inner tube along the inner surface ofthe central region to form a unitary tubular element prior to anyportion of the ring being located over any portion of the centralregion.
 17. The method of claim 14, wherein the vent passage comprises aslot formed in an outer surface of the central region and extending atleast partially across the central region, or formed in an inner surfaceof the ring and extending at least partially over the central region, orboth.
 18. The method of claim 14, wherein the central region of theinner tube comprises a raised portion formed on an outer surface of theinner tube, and wherein the ring is disposed entirely over the raisedportion of the central region.
 19. The method of claim 14, comprising:coupling the first flexible pipe to the first jacket via at least one ofswaging, bolting, gluing, or welding; and coupling the second flexiblepipe to the second jacket via at least one of swaging, bolting, gluing,or welding.
 20. The method of claim 14, coupling the ring to the innertube via threads, and wherein the vent passage comprises helical gaps inthe threads.